Conventionally, a known optical scanning apparatus scans an object of observation by irradiating light towards the object of observation from an optical fiber while displacing the emission end of the optical fiber and detects light that is reflected, scattered, or the like by the object of observation, fluorescent light generated on the object of observation, and the like (for example, see JP 2013-244045 A (PTL 1)).
The optical scanning apparatus disclosed in PTL 1 is provided with an optical scanning actuator that displaces the emission end of the optical fiber. The optical scanning actuator for example includes a ferrule and piezoelectric elements mounted on the side surfaces of the ferrule. The ferrule has a quadrangular prism shape and holds the emission end of the optical fiber, which passes through the ferrule.